Nano materials generate great benefits as well as new potential risks. Animal studies and in vitro experiments show that nanoparticles can result in lung damage and other toxicity, but no reports on the clinical toxicity in humans due to nanoparticles have yet been made.The present study aimed to examine the relationship between a group of workers' presenting with mysterious symptomatic findings and their nanoparticle exposure.Seven young female workers (aged 18-47 yrs), exposed to nanoparticles for 5-13 months, all with shortness of breath and pleural effusions were admitted to hospital. Immunological tests, examinations of bacteriology, virology and tumour markers, bronchoscopy, internal thoracoscopy and video-assisted thoracic surgery were performed. Surveys of the workplace, clinical observations and examinations of the patients were conducted.Polyacrylate, consisting of nanoparticles, was confirmed in the workplace. Pathological examinations of patients' lung tissue displayed nonspecific pulmonary inflammation, pulmonary fibrosis and foreign-body granulomas of pleura. Using transmission electron microscopy, nanoparticles were observed to lodge in the cytoplasm and caryoplasm of pulmonary epithelial and mesothelial cells, but are also located in the chest fluid. These cases arouse concern that long-term exposure to some nanoparticles without protective measures may be related to serious damage to human lungs.

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Accumulating studies in animals have shown that nanoparticles could cause unusual rapid lung injury and extrapulmonary toxicity. Whether exposure of workers to nanoparticles may result in some unexpected damage as seen in animals is still a big concern. We previously reported findings regarding a group of patients exposed to nanoparticles and presenting with an unusual disease. The reported disease was characterized by bilateral chest fluid, pulmonary fibrosis, pleural granuloma, and multiorgan damage and was highly associated with the nanoparticle exposure. To strengthen this association, further information on exposure and the disease was collected and discussed. Our studies show that some kinds of nanomaterials, such as silica nanoparticles and nanosilicates, may be very toxic and even fatal to occupational workers exposed to them without any effective personal protective equipment. More research and collaborative efforts on nanosafety are required in order to prevent and minimize the potential hazards of nanomaterials to humans and the environment.

Nanomaterials are increasingly being used for commercial purposes. However, concerns about the potential risks of exposure to humans have been raised. We previously reported unusual pulmonary disease and death in a group of patients with occupational exposure to spray paint. However, the nanoparticle and chemical composition of the exposure was not fully described. The present study aimed to isolate and identify the nanoparticles observed in the patients' biopsies and report the potential deleterious effects to human lungs using electron microscopy. Using electron microscopy and energy dispersive x-ray analysis, silica nanoparticles were identified and characterized mainly in macrophages, pulmonary microvessels, vascular endothelial cells, microlymphatic vessels, pleural effusions, and a few in alveolar epithelial cells and pulmonary interstitial tissue (with no microscale particles present). Notably, damage to alveolar epithelial cells, macrophages, vascular endothelial cells, and the blood-gas barrier was observed. Given the well-documented toxicity of microscale silica, it is possible that these silica nanoparticles may have contributed in part to the illness reported in these workers. Such a possibility supports the adoption of controls and prevention strategies to minimize inhalation of nanoparticles by workers, and it highlights the urgent need and the importance of the nanosafety study in humans.